Copper, renowned for its exceptional electrical and thermal conductivity at a low cost, holds great promise in electronic applications. While additive manufacturing of copper has attracted interest, the exploration of applying Drop-on-demand Metal Jetting (DoD-MJ) to 3D print pure copper remains uncharted. To fill this research gap, we employed an in-house DoD-MJ platform, MetalJet, to generate Cu microdroplets and deposit them onto ceramic and metallic substrates, a first-time achievement in this research context. Our study demonstrates the successful generation of uniform Cu microdroplets, emphasising the pivotal role of oxygen content control in preventing nozzle-level reactions, a factor that can disrupt droplet formation. Both alumina and aluminium nitride substrates exhibited poor wettability with molten Cu droplets, and no interface formed between these surfaces due to thermodynamically unfavourable reactions. Nevertheless, the irregular surface of alumina displayed an interesting capability to enable the adhesion of Cu droplets to the substrate through an interlocking mechanism. Lastly, the electrical resistivity of MetalJet printed pillars was measured as low as without any post-treatment, offering exciting possibilities for applications in 3D electronics.

中文翻译：

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纯铜的按需滴金属喷射：关于熔融金属与陶瓷和金属基材的相互作用

铜以其优异的导电性和导热性且成本低廉而闻名，在电子应用中具有广阔的前景。虽然铜的增材制造引起了人们的兴趣，但将按需金属喷射 (DoD-MJ) 应用于 3D 打印纯铜的探索仍然未知。为了填补这一研究空白，我们采用了 DoD-MJ 内部平台 MetalJet 来生成铜微滴并将其沉积到陶瓷和金属基材上，这是该研究领域的首次成就。我们的研究证明了均匀铜微滴的成功生成，强调了氧含量控制在防止喷嘴级反应中的关键作用，喷嘴级反应是破坏液滴形成的因素。氧化铝和氮化铝基材对熔融铜滴的润湿性较差，并且由于热力学不利反应，这些表面之间没有形成界面。然而，氧化铝的不规则表面显示出一种有趣的能力，可以通过联锁机制将铜液滴粘附到基材上。最后，经测量，MetalJet 打印柱的电阻率低至无需任何后处理，为 3D 电子学应用提供了令人兴奋的可能性。